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Current sensor and mounting method thereof

a current sensor and mounting method technology, applied in the field of current sensors, can solve the problems of reducing measurement accuracy, causing measurement errors of sensors, and difficult to carry out large current measurements, and achieve the effect of reducing measurement errors

Active Publication Date: 2008-04-08
MITSUBISHI ELECTRIC CORP +1
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Benefits of technology

The present invention provides a current sensor and mounting method that can reduce measurement errors caused by elongation or strain on the mounting substrate due to temperature or external electric field. The current sensor has a first half bridge circuit and a second half bridge circuit placed point symmetrically about the central point of the mounting substrate. This configuration ensures that the first and second half bridge circuits are equally affected by elongation or strain, which cancels out the effect and reduces the measurement error.

Problems solved by technology

With the foregoing configuration, the conventional current sensor has a problem of causing a measurement error because of the lost of the balance between left and right of the bridge circuit placed mirror symmetrically if elongation or strain occurs isotropically on a mounting substrate, on which the four magnetoresistive elements are mounted, because of temperature or the like.
In addition, it has a problem of making it difficult to carry out large current measurement.
Furthermore, since is takes no countermeasures against external electric field, it has a problem of reducing measurement accuracy when a noise source is close.

Method used

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Examples

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embodiment 1

[0022]FIG. 1 is a plan view showing the measured current detecting section of the current sensor of an embodiment 1 in accordance with the present invention. In FIG. 1, the measured current detecting section 1 is composed of circuit components which are arranged on a mounting substrate 2 in point symmetry with respect to the central point 4 on the center line 3 of the mounting substrate 2. Four magnetoresistive elements (first to fourth magnetoresistive elements) 5a-5d are placed in parallel to each other with respect to the center line 3 of the mounting substrate 2. A barber pole electrode structure is formed in such a manner that the magnetoresistive elements 5a and 5d have magnetoresistive characteristics of increasing the resistances with an increase of the magnetic fields opposite to each other in directions, and that the magnetoresistive elements 5b and 5c have magnetoresistive characteristics of reducing the resistances with an increase of the magnetic fields opposite to each...

embodiment 2

[0064]FIG. 8 is a plan view showing the measured current detecting section of the current sensor of an embodiment 2 in accordance with the present invention. In FIG. 8, four magnetoresistive elements (first to fourth magnetoresistive elements) 25a-25d are placed perpendicularly to the center line 3 of the mounting substrate 2; and a barber pole electrode structure is formed in such a manner that the magnetoresistive elements 25a and 25d have magnetoresistive characteristics of increasing the resistances with an increase of the magnetic fields opposite to each other in directions, and that the magnetoresistive elements 25b and 25c have magnetoresistive characteristics of reducing the resistances with an increase of the magnetic fields opposite to each other in directions.

[0065]Connecting current lines 26 constitute the bridge circuit by interconnecting the four magnetoresistive elements 25a-25d.

[0066]In the configuration shown in FIG. 8, the individual counterparts on the mounting s...

embodiment 3

[0082]FIG. 10 is a cross-sectional view showing a current sensor of an embodiment 3 in accordance with the present invention. In FIG. 10, an electric field shield layer (electric field shield cover) 31 covers the measured current detecting section 1 via an insulating layer 32. Since the remaining configuration is the same as that of FIG. 7, its duplicated description will be omitted here.

[0083]Next, the operation will be described.

[0084]As shown in FIG. 10, to shield the measured current detecting section 1 from a disturbance electric field, it is covered with the electric field shield layer 31 via the insulating layer 32.

[0085]The electric field shield layer 31, which is composed of an electrically conductive nonmagnetic material, is grounded although not shown in FIG. 10. Although only the measured current detecting section 1 is covered in the present embodiment 3, a case-like electric field shield cover can also be used which covers the whole device including the base 12. Providi...

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Abstract

A current sensor that can reduce a measurement error due to isotropic elongation or strain owing to temperature and the like. A first half bridge circuit is placed in a first region divided by a center line of a mounting substrate, and a second half bridge circuit is placed in a second region, and the half bridge circuits are equally formed and placed point symmetrically about the central point of the mounting substrate. Even if elongation or strain occurs isotropically in the mounting substrate of magnetoresistive elements owing to temperature, the half bridge circuits undergo the influence of the elongation or strain equally as the bridge circuit. Thus, it can cancel the effect and reduce the measurement error due to the isotropic elongation or strain owing to temperature.

Description

BACKGROUND OF THE INVENTION[0001]1. Field of the Invention[0002]The present invention relates to a current sensor for measuring the current flowing through a current line to be measured and a mounting method thereof.[0003]2. Description of Related Art[0004]As a conventional current sensor, there is one that places a bridge circuit consisting of four magnetoresistive elements mirror symmetrically (see Patent Document 1, for example).[0005]Patent Document 1: Japanese patent application laid-open No. 8-211138 / 1996.SUMMARY OF THE INVENTION[0006]With the foregoing configuration, the conventional current sensor has a problem of causing a measurement error because of the lost of the balance between left and right of the bridge circuit placed mirror symmetrically if elongation or strain occurs isotropically on a mounting substrate, on which the four magnetoresistive elements are mounted, because of temperature or the like.[0007]In addition, it has a problem of making it difficult to carry o...

Claims

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Application Information

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Patent Type & Authority Patents(United States)
IPC IPC(8): G01R15/20
CPCG01R15/205G01R33/09G01R33/096G01R17/10
Inventor OKADA, AKIRAMIYAMOTO, JUNJI
Owner MITSUBISHI ELECTRIC CORP